Fix my wife's mouth (dental surgery)

My wonderful wife Brenda has three autoimmune diseases, and while she does take wonderful care of her teeth (she brushes, flosses, and fights off the Cavity Creeps just fine), because of her autoimmune issues, her teeth are weak. She has a couple broken teeth, and recently we've discovered one of them needs to be taken out and an implant put in its place. This entire process will take several months and at least three appointments. The dentist's office (Gentech Dentist) has estimated that the first phase (the costliest) will cost just under $600 after insurance.

This became an immediate issue several weeks ago when she started experiencing extreme pain in her lower jaw (where the rogue tooth is) that was so bad, her lips started going numb. An abscess had formed around this tooth, and while it was treated with antibiotics, if the tooth isn't removed and replaced, the chances of another abscess forming are greater. And because of her autoimmune diseases (rheumatoid arthritis being one of the big ones), her immune system is already weakened which means infections like the last abscess are not something we can take lightly.

My wife doesn't know I'm doing this. I will tell her if any funds can be raised, of course. At this point, we're living paycheck-to-paycheck, so this dentist bill is not something we'll be able to handle easily.